Pushing the .body back into FogInterface

These should all be in FogInterface rather than this leaking out into our code.
I wanted to wait to refactor until the test was complete but this is making it
really hard to test the provision method. Integration test passes and unit tests
all pass.
A basic unit test for the provision method

This will very probably be thrown away - and if not will be very much modified,
but I wanted a test round the provision method before we start refactoring. I
went down many rabbit holes before eventually making one small change (previous
commit) in order to get this test to pass.

Some refactoring to do even in the test - not sure we need everything we've
mocked - but that's a task for another day.

cc /@mikepea
[#60082842] Testing PT hook
[#60082842] Test that missing vApp template exits
Merge branch 'unit-test-coverage' of github.com:alphagov/vcloud-tools into unit-test-coverage
[#60082842] Tidy template handling from Vapp

* Split into own class
[#60082842] Adding failing test

Next step - implementation of raising the exception. TDD FTW!
[#60082842] more tests for Template object
[#60082842] switch to exception handling in provision
[#60082842] Raise RuntimeError instead of exiting
[#60082842] reduce test output

* expect logging

* remove debug code
[#60082842] sensible test data names
remove test commit from README
remove test commit from README
Merge pull request #18 from alphagov/unit-test-coverage

Unit test coverage